JPH048448B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a novel optically anisotropic polyester that can be melt-molded at 450° C. or lower and can provide molded articles having excellent mechanical properties and optical anisotropy. <Conventional technology> In recent years, the demand for higher performance plastics has been increasing, and many polymers with various new performances have been developed and offered on the market. Optically anisotropic liquid crystal polymers have attracted attention because of their excellent mechanical properties. Fully aromatic polyesters are widely known as liquid crystal polymers, and for example, homopolymers and copolymers of p-hydroxybenzoic acid are called "EKONOL".
It is sold under the trademark . However, p-
Hydroxybenzoic acid homopolymer has a too high melting point and cannot be melt-molded, so p-
Methods of copolymerizing hydroxybenzoic acid with various components to lower its melting point have been studied; for example, p-
Hydroxybenzoic acid, phenylhydroquinone,
Method for copolymerizing terephthalic acid and/or 2,6-naphthalene dicarboxylic acid (Publication Patent Publication No. 55-
500215), and a method of copolymerizing 2.6 dihydroxynaphthalene and terephthalic acid with p-hydroxybenzoic acid (Japanese Patent Application Laid-open No. 50594/1983). <Problems to be solved by the invention> However, while the optically anisotropic polyester obtained by these methods has a relatively low melting point of 450°C or less,
The elastic modulus of the spun yarn is still insufficient, and an even higher elastic modulus is desired. Therefore, the present inventors conducted intensive studies with the aim of obtaining an optically anisotropic polyester that is melt moldable and has an excellent balance between mechanical properties represented by a high modulus of elasticity and optical anisotropy, and found that p-hydroxybenzoic acid and hydroquinone, 4,4'-diphenyldicarboxylic acid, and terephthalic acid (JP-A-58-91721); and phenylhydroquinone, 4,4'-diphenyldicarboxylic acid (JP-A-59-1999). -41329) and a polyester consisting of p-hydroxybenzoic acid, phenylhydroquinone, and 4,4'-diphenyldicarboxylic acid (Japanese Unexamined Patent Application Publication No. 1983-41328), and filed an application based on the discovery that they give molded products with high elastic modulus. However, it was discovered that a polyester having the following structure has an even higher modulus of elasticity, and the present invention was completed. <Means for solving the problems> That is, the present invention has the following structural units () to
It consists of () and the unit () is [() + () + ()
]
0 to 90 mol%, unit [() + ()] of the whole
It consists of 100 to 10 mol%, and the units [()+()] and [()+()] are in substantially equal molar proportions, and the molar ratio of ()/[()+()] is 1.0 to 0.2, the molar ratio of ()/[()+()] is 1.0 to 0.5 (liquid crystal starting temperature +80℃), and the shear rate is 3000 (1/
The present invention provides a melt-moldable optically anisotropic polyester characterized by a melt viscosity measured in seconds) of 10 to 15,000 poise and a liquid crystal onset temperature of 400°C or less. -(O-X-O-) ...() (However, X in the formula is

【formula】

【formula】

【formula】

【formula】

【formula】

[expression] and

Indicates a group selected from [Formula], Y teeth

【formula】

【formula】

【formula】

[expression] and

Indicates one or more groups selected from [Formula]. However, Y consists of the units (), (), (), and ().

Combination and unit consisting of [formula] (), (), (), and X is

(excluding combinations consisting of [expression]). In the optically anisotropic polyester of the present invention, the above structural unit () represents a structural unit of a polyester produced from p-hydroxybenzoic acid. In addition, the structural units () and () are structural units obtained by removing the hydrogen atom of the hydroxy group of aromatic dihydroxy compounds such as hydroquinone, and the structural units () and () are structural units obtained by removing the hydrogen atom from the hydroxy group of aromatic dihydroxy compounds such as hydroquinone. It shows the structural unit obtained by removing the hydroxyl group of a dicarboxylic acid, and shows each structural unit when an aromatic dihydroxy compound and an aromatic dicarboxylic acid are polymerized in a substantially equimolar ratio. The optically anisotropic polyester of the present invention has a melting point of
The temperature is 450°C or less, and it is possible to easily mold fibers, films, and various molded products with excellent mechanical properties by ordinary melt molding. For example, a polyester consisting of p-hydroxybenzoic acid, hydroquinone, 4,4'-diphenyldicarboxylic acid, and terephthalic acid described in JP-A No. 58-91721 has a relatively low melting point of 450°C or less and is elastic. Although the optically anisotropic polyester of the present invention has a relatively high value of 60 GPa, the optically anisotropic polyester of the present invention has the advantage of having better melt flowability and significantly higher elastic modulus than the polyester described in the above-mentioned publication. In the optically anisotropic polyester of the present invention, the above-mentioned structural unit () is preferably 0 to 90 mol%, particularly preferably 15 to 80 mol%. Unfavorable because properties deteriorate. ()/[()
+()] molar ratio is 1.0 to 0.2, preferably 1.0
~0.3. On the other hand, the molar ratio of ()/[()+()] is 1.0~
0.5, preferably 1.0 to 0.55. The aromatic dihydroxy components forming the structural unit () in the optically anisotropic polyester of the present invention include chlorohydroquinone, methylhydroquinone, phenylhydroquinone, tert-butylhydroquinone, 4,4'-dihydroxybiphenyl, 2, 6-dihydroxynaphthalene, 2,7-
It is a component selected from dihydroxynaphthalene. In addition, the dicarboxylic acid component forming the above structural unit ( 2-
One or more dicarboxylic acid components selected from chlorophenoxy)ethane-4,4'-dicarboxylic acid and 4,4'-dicarboxydiphenyl ether. Among these, phenylhydroquinone or
tert-butylhydroquinone. The optically anisotropic polyester of the present invention can be produced according to conventional polyester polycondensation methods, and there are no particular restrictions on the production method, but typical production methods include the following methods (1) to (3). . (1) Demonocarboxylic acid polycondensation of aromatic dicarboxylic acids mainly consisting of p-acetoxybenzoic acid and diesters of aromatic dihydroxy compounds such as hydroquinone diacetate and hydroquinone dipropionate and 4,4'-diphenyl dicarboxylic acid. A method of manufacturing by. (2) A method for producing phenyl esters of p-oxybenzoic acid and aromatic dihydroxy compounds such as hydroquinone by dephenol polycondensation from diphenyl esters such as 4,4'-diphenyldicarboxylic acid. (3) Aromatic dicarboxylic acids, mainly p-oxybenzoic acid and 4,4'-diphenyldicarboxylic acid, are reacted with a desired amount of diphenyl carbonate to form diphenyl esters, and then aromatic dicarboxylic acids such as hydroquinone are reacted with the desired amount of diphenyl carbonate. A method of manufacturing by adding a dihydroxy compound and performing a phenol-free polycondensation reaction. Acetic acid No. 1 is used as a catalyst for polycondensation reaction.
Metal compounds such as tin, tetrabutyl titanate, lead acetate, sodium and potassium acetate, and antimony trioxide are representative, and are particularly effective in dephenol polycondensation. Some of the optically anisotropic polyesters of the present invention can be measured for intrinsic viscosity in pentafluorophenol, and in that case, the intrinsic viscosity is 0.1 (weight/volume).
% concentration measured at 60° C. is preferably 0.35 or more, particularly preferably 0.4 to 15.0. Further, the melt viscosity of the optically anisotropic polyester of the present invention is 10 to 15,000 poise, particularly preferably 50 to 10,000 poise. In addition, this melt viscosity is (liquid crystal starting temperature + 80℃)
This is a value measured using a Koka type flow tester at a shear rate of 3000 (1/sec). In addition, when polycondensing the optically anisotropic polyester of the present invention, isophthalic acid, 3,3'-diphenyldicarboxylic acid, 3,4'-diphenyl dicarboxylic acid, Aromatic dicarboxylic acids such as enyldicarboxylic acid and 2,2'-diphenyldicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, and others such as m-oxybenzoic acid and 2,6-oxynaphthoic acid. Aromatic oxycarboxylic acids and the like can be further copolymerized within a small proportion that does not impair the object of the present invention. The optically anisotropic polyester of the present invention thus obtained has a low liquid crystal initiation temperature or melting point of 400°C or less,
It can be subjected to conventional melt molding such as extrusion molding, injection molding, compression molding, and blow molding, and can be processed into fibers, films, three-dimensional molded products, containers, hoses, etc. During molding, reinforcing agents such as glass fiber, carbon fiber, and asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and Additives such as flame retardants and other thermoplastic resins can be added to impart desired properties to the molded article. The molded article obtained from the novel optically anisotropic polyester of the present invention has good optical anisotropy due to its parallel molecular arrangement and has extremely excellent mechanical properties. The strength of the thus obtained molded product can be increased by heat treatment, and the elastic modulus can also be increased in many cases. This heat treatment can be carried out by heat treating the molded article in an inert atmosphere (eg nitrogen, argon, helium or water vapor) or in an oxygen-containing atmosphere (eg air) at a temperature below the melting point of the polymer. This heat treatment may or may not be under tension and can be carried out for a period of several minutes to several days. <Examples> The present invention will be further explained below with reference to Examples. Example 1 6.48 g of p-acetoxybenzoic acid in a polymerization test tube
(3.6×10 ^-2 ), hydroquinone diacetate 2.33g
(1.2 x 10 ^-2 ), 3.0 g (1.2 x 10 ^-2 mol) of tert-butylhydroquinone diacetate and 5.81 g (2.4 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid under the following conditions. Acetic acid depolymerization was performed. First, the reaction was carried out at 250 to 350°C for 3.0 hours in a nitrogen gas atmosphere, then the pressure was reduced to 0.5 mmHg at 350°C, and the reaction was further carried out for 1.0 hours to complete the polycondensation.
Approximately the theoretical amount of acetic acid was distilled out and a brown polymer was obtained. The theoretical structural formula of this polymer is as follows,
The elemental analysis results of the polyester showed good agreement with the theoretical values as shown in Table 1. Further, the thermal properties of this polymer were measured using a differential scanning calorimeter (Perkin-Elmer type), and the melting point was 26.5°C.

[Table] However, the oxygen content (%) is (100%-C%-H
%). In addition, this polyester was placed on the sample stage of a polarizing microscope, and the temperature was raised and shear was added to confirm the optical anisotropy.As a result, the liquid crystal initiation temperature was 260°C, indicating good optical anisotropy. This polyester was subjected to a flow tester and spun at a spinning temperature of 340°C and a spinneret hole diameter of 0.3 mmφ.
A spun yarn of mmφ was obtained. The melt viscosity was 1500 poise at 340°C and a shear rate of 3000 (1/sec). This spun yarn was processed at a frequency of 110Hz using a Leoviblon DDV--EA manufactured by Toyo Baldwin Co., Ltd.
When the elastic modulus was measured at a heating rate of 2°C/min and a chuck distance of 40 mm, the elastic modulus was extremely high at 30°C, 108 GPa. Example 2 5.4 g of p-acetoxybenzoic acid in a polymerization test tube
(3×10 ^-2 mol), hydroquinone diacetate
5.82 g (3 x 10 ^-2 mol), 3.63 g (1.5 x 10 ^-2 mol) of 4,4'-diphenyldicarboxylic acid, and 3.24 g (1.5 x 10 ^-2 mol) of 2,6-naphthalene dicarboxylic acid were carried out. The polycondensation reaction was carried out under the same conditions as in Example 1. The theoretical structural formula of this polyester is as follows, and the elemental analysis results of this polyester were in good agreement with the theoretical values as shown in Table 2. The thermal properties of this polymer were measured using a differential scanning calorimeter (Perkin Elmer type), and the melting point was 279°C.

[Table] However, the oxygen content (%) is (100%-C%-H
%). Furthermore, the optical anisotropy was confirmed by placing this polyester on the sample stage of a polarizing microscope and raising the temperature. As a result, the liquid crystal initiation temperature was 256° C., indicating good optical anisotropy. The logarithmic viscosity of this polyester was measured with pentafluorophenol (0.1 g/dl concentration, 60°C) and was found to be 3.9 dl/g. This polyester was subjected to a flow tester and spun at a spinning temperature of 340°C and a nozzle hole diameter of 0.3 mmφ.
A spun yarn of mmφ was obtained. The melt viscosity was 1500 poise at 336°C and a shear rate of 3000 (1/sec). The elastic modulus of this spun yarn was measured using a Rheoviblon DDV--EA manufactured by Toyo Baldwin Co., Ltd. at a frequency of 110 Hz, a heating rate of 2°C/min, and a distance between chucks of 40 mm, it was found to be 127 GPa at 30°C. It had a high elastic modulus. Comparative Example 1 10.08 p-acetoxybenzoic acid in a polymerization test tube
g (5.6 x 10 ^-2 mol), hydroquinone diacetate 2.72 g (1.4 x 10 ^-2 mol), 2,6-naphthalene dicarboxylic acid 2.27 g (1.05 x 10 ^-2 mol), isophthalic acid 0.58 g (0.35 x 10 ^Example 1
Polycondensation was carried out at a reaction temperature of 330°C according to the conditions described above to obtain an optically anisotropic polyester with a melting point of 281°C. Using this polyester, spinning was carried out at a spinning temperature of 340°C to obtain a spun yarn of 0.06 mmφ, and its elastic modulus was measured, and it was found to be 56 GPa at 30°C, which was lower than the polyester of the present invention. Examples 3 to 13, Comparative Examples 2 to 4 p-acetoxybenzoic acid (),
Hydroquinone diacetate (), chlorhydroquinone diacetate (), methylhydroquinone diacetate (), phenylhydroquinone diacetate (), tert-butylhydroquinone diacetate (), 4,4'-diacetoxybiphenyl (), 2 , 6-diacetoxynaphthalene (), 2,7-diacetoxynaphthalene (), and 4,
4'-diphenyldicarboxylic acid (), 2,6-naphthalenedicarboxylic acid (XI), 1,2-bis(2
-chlorophenoxy)ethane-4,4'-dicarboxylic acid (XII), 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid (), and terephthalic acid (), respectively.
A polycondensation reaction was carried out in the same manner as in Example 1 by charging the components into a polymerization test tube so that the diacetate component=the number of moles of the dicarboxylic acid component as shown in the table. When the optical anisotropy of the obtained polymer was confirmed, it was found that all the polyesters of the present invention (Examples 3 to 13) exhibited good optical anisotropy as shown in Table 3. On the other hand, polyesters other than those of the present invention (Comparative Examples 2 to 4) had high liquid crystal initiation temperatures, high melt viscosity, and poor fluidity.

[Table] <Effects of the Invention> The aromatic polyester of the present invention can be melt-molded and molded products with high elastic modulus can be obtained.
It can be used for various purposes such as engineering plastics as a metal substitute plastic.

Claims (1)

[Claims] 1 Consisting of the following structural units () to () ()
is 0 to 90 mol% of [() + () + ()], unit [() + ()] is 10 of [() + () + ()]
0-10
Consists of mol%, with units [()+()] and [()+
()] in substantially equimolar proportions;
The molar ratio of ()/[()+()] is 1 to 0.2, the molar ratio of ()/[()+()] is 1 to 0.5, (liquid crystal starting temperature +80°C), shear rate 3000 (1/
An optically anisotropic polyester that can be melt molded and has a melt viscosity of 10 to 15,000 poise measured in seconds) and a liquid crystal onset temperature of 400°C or less. -(O-X-O-) ...() (However, X in the formula represents a group selected from [formula] [formula] [formula] [formula] [formula] [formula] and [formula], and Y represents a group selected from [formula] [formula] [formula] [formula] ] and [Formula]. However, the units (), (), (), (), (
)
(excluding combinations where Y is [formula] and units (), (), () and X is [formula]).